fix(Tree): corrects lookup issue with catch all and shared key

Lookup was failing when part of the given path matched a key at the
first character, even when the rest of the key didn't match.

It was not possible place a catch all an another key at the same
level that started with same character.

This change ensures that all shared part between path and key is
compared prior assuming usage of that node as part of the lookup.

Closes #14

CHANGELOG.md

@@ -5,6 +5,8 @@ This project aims to comply with [Semantic Versioning](http://semver.org/),
 so please check *Changed* and *Removed* notes before upgrading.
 
 ## [Unreleased]
+### Fixed
+- Correct lookup issue when dealing with catch all and shared partial key (@crisward)
 
 ## [0.3.4] - 2016-11-12
 ### Fixed

spec/radix/tree_spec.cr

@@ -404,6 +404,18 @@ module Radix
           result.found?.should be_true
           result.key.should eq("/members")
         end
+
+        it "does prefer catch all over specific key with partially shared key" do
+          tree = Tree(Symbol).new
+          tree.add "/orders/*anything", :orders_catch_all
+          tree.add "/orders/closed", :closed_orders
+
+          result = tree.find("/orders/cancelled")
+          result.found?.should be_true
+          result.key.should eq("/orders/*anything")
+          result.params.has_key?("anything").should be_true
+          result.params["anything"].should eq("cancelled")
+        end
       end
 
       context "dealing with named parameters" do

src/radix/tree.cr

@@ -313,9 +313,10 @@ module Radix
         # not found in current node, check inside children nodes
         new_path = path_reader.string.byte_slice(path_reader.pos)
         node.children.each do |child|
-          # check if child first character matches the new path
+          # check if child key is a named parameter, catch all or shares parts
-          if child.key[0]? == new_path[0]? ||
+          # with new path
-             child.key[0]? == '*' || child.key[0]? == ':'
+          if (child.key[0]? == '*' || child.key[0]? == ':') ||
+             _shared_key?(new_path, child.key)
             # consider this node for key but don't use payload
             result.use node, payload: false
 
@@ -376,6 +377,16 @@ module Radix
       count
     end
 
+    # Internal: allow inline comparison of *char* against 3 defined markers:
+    #
+    # - Path separator (`/`)
+    # - Named parameter (`:`)
+    # - Catch all (`*`)
+    @[AlwaysInline]
+    private def _check_markers(char)
+      (char == '/' || char == ':' || char == '*')
+    end
+
     # Internal: Compares *path* against *key* for differences until the
     # following criteria is met:
     #
@@ -409,6 +420,40 @@ module Radix
         (path_reader.current_char == '/' || !path_reader.has_next?)
     end
 
+    # Internal: Compares *path* against *key* for equality until one of the
+    # following criterias is met:
+    #
+    # - End of *path* or *key* is reached.
+    # - A separator (`/`) is found.
+    # - A named parameter (`:`) or catch all (`*`) is found.
+    # - A character in *path* differs from *key*
+    #
+    # ```
+    # _shared_key?("foo", "bar")         # => false (mismatch at 1st character)
+    # _shared_key?("foo/bar", "foo/baz") # => true (only `foo` is compared)
+    # _shared_key?("zipcode", "zip")     # => true (only `zip` is compared)
+    # ```
+    private def _shared_key?(path, key)
+      path_reader = Char::Reader.new(path)
+      key_reader = Char::Reader.new(key)
+
+      different = false
+
+      while (path_reader.has_next? && !_check_markers(path_reader.current_char)) &&
+            (key_reader.has_next? && !_check_markers(key_reader.current_char))
+        if path_reader.current_char != key_reader.current_char
+          different = true
+          break
+        end
+
+        path_reader.next_char
+        key_reader.next_char
+      end
+
+      (!different) &&
+        (!key_reader.has_next? || _check_markers(key_reader.current_char))
+    end
+
     # :nodoc:
     private def deprecation(message : String)
       STDERR.puts message